Continued reduction in transistor sizes following Moore's Law has provided the technological basis for marked circuit performance improvements, making possible billion-transistor integrated circuits operating at gigahertz frequencies. The smaller size of these devices, however, results in increased fabrication difficulty, higher power densities, and parasitic effects that threaten to limit the further improvement of Si-based circuits [1, 2]. In an effort to provide continued improvements in computing performance, newly available materials and devices have been evaluated as building blocks for next-generation computing [3]. These technologies include devices derived from single-electron transistors [4], carbon nanotubes [5] and related graphene structures [6, 7], nanowires [7, 8], and molecular switches [9]. Additionally, there has been much interest in devices and logic techniques that utilize electron spin [10-20].
The emergence of new materials and devices has inspired reconsideration of conventional logic styles and circuit architectures. While complementary metal-oxide-semiconductor (CMOS) transistors and the accompanying CMOS logic family have dominated Si-based circuits [21], other devices and logic families have significant advantages. Diode logic is elegant in several respects, such as simple OR gates and single junction devices that allow for compact circuit structures. Circuits based on diode logic use fewer devices than their CMOS counterparts, and therefore potentially consume less power and area while operating at higher speeds. Diode logic, however, has historically been impractical due to the inability of a diode to behave as an inverter [22]. As inversion is a necessary function of a complete logic family, diodes, previous to these results, could only perform complex logic functions in concert with transistors.
Therefore, a heretofore unaddressed need exists in the art to address the aforementioned deficiencies and inadequacies.